1. Field of the Invention
The present invention relates to a color extraction apparatus and method for extracting a particular color from an input color image signal. For example, the invention is applied to realizing, in an entertainment robot or an imaging system, a function of recognizing a target object having a particular color and following it automatically.
2. Description of the Related Art
As disclosed in, for instance, Japanese Unexamined Patent Publication No. Hei. 8-51564, in conventional target following apparatuses and the like in which the imaging direction is controlled by detecting the movement of a target from an image taken by a television camera, it is operated to follow a target by using color information of a color image signal in addition to shape information of a target.
As proposed in Japanese Patent Application Nos. Sho. 59-12481 and Hei. 5-329272, a color extraction technique is known in which a color is extracted by normalizing input chrominance signals by an input luminance signal and comparing normalized signals with a preset value.
However, this conventional color extraction technique including normalization has a limitation that color models in a luminance/chrominance space are restricted.
The assignee of the present application has proposed a technique in which a high-order color model is introduced and a judgment is made by calculating the distance between a model and an input image with a microcomputer (Japanese Patent Application No. Hei. 9-48786). However, in this type of technique in which limitations on models are eliminated by using a microcomputer, the execution speed and the capability of accommodating a plurality of colors are insufficient because an input image is processed by the microcomputer.